Fluid level alarm and control device

ABSTRACT

A gas operated audible alarm device is provided to signal the advent of an overlow or leakage condition in oil tanks and the like to minimize the hazards of environmental pollution from oil and chemical spills during tank filling operations. The device has a float operated pneumatic valve positioned at a predetermined upper limit of fluid level in a receiving tank, which valve controls the passage of an inert gas from a supply source to a gas operated whistle or horn in response to an overflow or leakage condition sensed by the float. In one embodiment the alarm device may be placed in the rakes of a barge or the bilge of a ship to sound an alarm in response to a sinking condition of the ship or barge. In another embodiment the source of gas is connected in circuit with a pressure sensitive switch which will actuate means to shut down the supply of oil in response to an overflow or leakage condition sensed in the oil tanks being filled.

United States Patent [191 Ward et al. I

[ FLUID LEVEL ALARM AND CONTROL DEVICE I [76] Inventors: John T. Ward, 6279 W. Rockhom Hill, Elkridge, Md. 21227; Allen B. Keller, 2914 Ontario Ave., Baltimore, Md. 21234 [22] Filed: June 15, 1973 [21] Appl. No.1 370,548

[52] U.S. Cl. 417/40, 73/308 [51] Int. Cl. F04!) 49/00, G01f 23/10 [58] Field of Search 417/40, 63, 6, 31, 36,

[56] References Cited UNITED STATES PATENTS 1,056,752 2/1912 Durdin, Jr 417/31 667,417 2/1902 Wright 137/102 3,675,614 7/1972 Ward et al... 116/118 282,620 8/1883 Forster 116/113 2,742,0l4 4/1956 Pleasants 116/109 FOREIGN PATENTS OR APPLICATIONS 793,262 4/1958 Great Britain 73/307 [451 Apr. 30,1974

Primary ExaminerCarlton R. Croyle Assistant Examiner-Arnold Ward I Attorney, Agent, or Firm-Herbert ,M. Birch; Terrell C. Birch; Anthony L. Birch [57] ABSTRACT A gas operated audible alarm device is provided to signal the advent of an overlow or leakage condition in oil tanks and the like to minimize the hazards of environmental pollution from oil and chemical spills during tank filling operations. The device has a float operated pneumatic valve positioned at a predetermined upper limit of fluid level in a receiving tank, which valve controls the passage of an inert gas from a supply source to a gas operated whistle or horn in response to an overflow or leakage condition sensed by the float. In one embodiment the alarm device may be placed in the rakes of a barge or the bilge of a ship to sound an alarm in response to a sinking condition of the ship or barge. In another embodiment the source of gas is connected in circuit with a pressure sensitive switch which will actuate means to shut down the supply of oil in response to an overflow or leakage condition sensed in the oiltanks being filled.

16 Claims, 9 Drawing Figures PATENTEU 1H! 30 I974 SHEET 2 0F 4 FLUID LEVEL ALARM AND CONTROL DEVICE BACKGROUND OF INVENTION The present invention is an improvement over US. Pat. No. 3,675,614 issued July 1 l, 1972 to the same inventors of the present invention. It is intended to incorporate by reference the disclosure of said US. Patent herein.

1. Field of Invention This invention relates to an audible alarm and control means-for sensing the level of a liquid or fluid. More particularly the present invention relates to an audible alarm and control means for sensing the level of fluid in oil tanks or the bilge or rakes of a ship,which sound an alarm or performs a control function in response to an undesirable fluid level which is sensed.

2. Description of Prior Art Many spills of oil and other undesirable substances which pollute the environment are occasioned by human error. One of the most common forms of human error is the'failure to detect that the fluid level in a tank being filled with oil or other fluid chemicals is immediately proximate to the overflow point of the tank.

Attempts have been made in the prior art to provide float actuated or pressure actuated audible alarm devices which provide an indication of the advent of an overflow condition in a storage tank. Such storage tanks may be fixed or ambulatory land-based tanks or located on cargo barges or other vessels.

Due to the highly flammable and/or reactive nature of many fluids contained in such storage tanks, electrical alarm systems are unduly expensive since they must be both corrosion resistant and spark free. Furthermore, alarm systems utilizing compressed air and compressed carbon dioxide as the activating medium for an audible whistle or similar device have numerous drawbacks based upon environmental problems such as freezing or unsafe reactions with the fluids contained in the tanks being monitored by the alarm devices.

OBJECTS OF INVENTION vide a new and novel audible alarm device and system for a plurality of such devices having a source of pressurized actuating fluid feeding each of a plurality of such audible alarm devices whereby an entire network of cargo or storage tanks can be successfully monitored to indicate the advent of overflow conditions in any given tank.

It is a further object of the present invention to pro vide an audible alarm device which can detect either a leakage condition in a tank in response to the fluid level falling below a predetermined minimum or an overflow condition in response to the fluid level in said tank exceeding a predetermined maximum.

It is still a further object of the present invention to provide an audible alarm device which is more com- It is yet another object of the present invention to provide an automatic control means for shutting down a tank filling operation in response to the same undesirable fluid level conditions which would generate an alarm signal.

These and other objects of the invention will become more fully apparent with reference to the following specification and drawings which relate to a preferred embodiment of the invention.

In the drawings: 7

FIG. 1 is a top plan view of an audible alarm device of the present invention and aportion of a system embodying same;

FIG. 2 is a perspective view of the audible alarm device of FIG. 1;

FIG. 3 is a side elevational view of the audible alarm device and portion of the system illustrated in FIG. I mounted in a suitable tank;

FIG. 4 is a top plan view of an audible alarm system of the present inventionmounted on a Ship or barge;

FIG. 5 is a side elevational view of the system of FIG.

FIG. 6 is a schematic view of the automatic control means of the present invention for automatically shutting down the filling operation of an oil barge;

FIG. 7 is another embodiment of the audible alarm device of the present invention which detects either an overflow or leakage condition in a tank;

FIG. 8 is a top plan view of the alarm device of FIG.

7; and

FIG. 9 is a front elevational view of the alarm device of FIG. 7.

Basically, the invention comprises a float actuated valve interconnecting a source of dry nitrogen gas under pressure through the said valve to a whistle or horn device adapted to be'actuated by gas under pressure. The alarm device is adapted to be positioned in the upper extremities of the interior of a' cargo or storage tank whereupon the float is responsive to the liquid level in the cargo or storage tank to actuate the valve and release nitrogen under pressure to the whistle when the level in the tank approaches an overflow condition. If a multiplicity of tanks isinvolved, each tank is provided with an individual audible alarm device connected to a supply header or manifold which in turn is connected to a source of pressurized dry nitrogen to drive the individual whistles on the audible alarm devices when the fluid level in any given tank approaches an overflow condition.

In another embodiment of the present invention an alarm device is provided including means for sounding said alarm in response to either an overflow condition or leakage condition in a cargo or storage tank. This is facilitated by including mechanical linkage means both above and below the float, both of said linkage means being coupled to the float actuated valve, for actuating said valve in response to either an overflow condition, wherein the fluid in said tank exceeds a predetermined level, or a leakage condition, wherein the fluid in said tank falls below a predetermined minimum.

In yet another embodiment of the invention the alarm device can be placed in the rakes or bilge of a ship to sound an alarm in response to a sinking condition of said ship.

In still another embodiment of the present invention the alarm devices of the present invention may be modified to generate an automatic control signal. For example the dry nitrogen gas under pressure which is released in response to a predetermined condition may simultaneously be used to actuate a pressure responsive control switch in response to said condition. In a preferred embodiment said pressure responsive control switch is adapted to actuate an electromagnetic control valve in the supply line of an oil pumping system located on a land based loading dock and a relay in the electrical circuit of the pumping system. Therefore, when an overflow, leakage, or other undesirable condition is sensed by said alarm device, said pressure responsive switch will generate a control signal to said electromagnetic control valve and relay in said pumping system, which automatically shuts down the supply of oil being pumped from said loading dock. This embodiment constitutes a significant advance in the art since an automatic shut down of the pumping operation occurs substantially simultaneously with the sounding of the alarm.

Referring in detail to the drawings and more particularly to FIGS. 1, 2 and 3, the audible alarm device of the present invention is shown as comprising a main mounting bracket 12 attached to an open frame 14 consisting of struts 11 and support ring 18. Extended from the open frame is a float constraining cage device 16 which is defined at an upper end by ring 18, a plurality of dependent struts 20, welded or otherwise fixed to the upper support ring 18, and a circular bottom plate 22, welded or otherwise fixed to the lower end of the vertical struts 20. The vertical struts 20 are substantially of identical length such that the lower support plate 22 is substantially parallel to the plane of the upper support ring 18.

A spherical float 24 is rigidly affixed to foot 36B of bell crank 36 by welding or other suitable means within float cage 16 and normally seats on the lower support plate 22 so long as the'level of the fluid in the tank being monitored is below the lower support plate 22.

Mounted in the open frame 14, through the bracket 12, is a valve assembly 26. The valve assembly 26 includes a plunger operated on-off type pneumatic valve 28 in-line mounted in a pneumatic manifold pipe 30 which extends from an input portion 30A through the main mounting bracket 12 through the valve 28 and thence back through the mounting bracket 12 to an output section 30B. Plunger 32 extends vertically above the valve 28 in response to a predetermined liquid level in a tank in which the alarm device- 10 is mounted.

The remainder of the actuating linkage for the valve 28 comprises an upstanding bifurcated pivot bracket 34 mounted on the body of the valve 28, in which a bell crank 36 is pivoted at a point 38 intermediate the ends thereof. Bell crank 36 is provided with an engaging foot 36A on one side of the pivot point 38 which is adapted to engage the plunger 32 on the valve 28. The other end of the bell crank 36 is provided with a contact foot The input side 30A of the pressure manifold 30 is connected to a supply header 40 which in turn is connected to a supply 42 of dry nitrogen gas under pressure through a filter 47. Filter 47 prevents foreign particles from entering and damaging the valve seat in valve 28; prevents'damage to the diaphragms of whistles 44 by foreign particles, such as metal shavings from pipe threading, dirt or rust in the pipes; and prevents damage to the regulator valve 48 of nitrogen supply 42. See FIG. 8. As shown in FIG. 3 nitrogen supply 42 is provided with a pressure regulator valve 48 having pressure gauges 50 mounted thereon. The output section 30B of the pressure manifold 30 is directly connected to a gas operated whistle 44 suitably mounted on top of tank T;

The fact that float 24 is rigidly affixed by welding or other suitable means to foot 368 of bell crank 36 offers contained within float cage 16.

distinct advantages over the audible alarm device disclosed in US. Pat. No. 3,675,614 issued July 1 1, 1972 to the same inventors as the present invention. In that patented device float 24 was freely constrained within float cage 16 wherein the float 24 had to rise at least 4 inches before contacting foot 36B of bell crank 36. In contradistinction the float 24 of the present invention is fixedly attached to foot 36B and need only travel about one quarter of an inch to raise bell crank 36 a sufficient distance to openvalve 28. This reduces the overall height necessary for cage 16 and, therefore, makes the audible alarm device of the present invention more compact. The structure of the present invention is also faster acting and decreases the probability of float 24 hanging up in cage 16, because float 24 travels only one quarter of an inch instead of 4 inches through cage 16 and is substantially constrained against lateral movement.

As shown in FIG. 3 the audible alarm device 10, is shown with the main mounting bracket 12 affixed to mounting brackets 12A and 12B affixed to the side wall 46 in the upper dome of tank T. The corners of mounting bracket 12 are angled instead of square. This feature in combination with the use of mounting brackets 12A'and 12B facilitates the mounting of alarm device 1 0 on either a flat or rounded surface.

It is of the utmost importance that the supply of pressurized inert gas be dry nitrogen gas in the present invention and its application. This is occasioned by the factthat ordinary compressed air may and many other readily available compressed gases would create highly flammable conditions within the tank due to their oxygen or other reactive gas content should there be a malfunction in the valve assembly 26 or the pressure manifold 30 within the tank T.

Furthermore, a commonly available inert gas, namely, carbon dioxide, has inherently bad qualities for alarm devices of this type due to environmental problems. For example, should there be an undue amount of moisture in the air or should the temperatures be relatively low in the atmosphere surrounding the tanks, the whistle 44, when subjected to a blast of carbon dioxide therethrough in order to sound the alarm, would freeze and preclude proper actuation.

Dry nitrogen, on the other hand, is readily available and will not create freezing conditions when released from a pressurized source to pass through a whistle under extreme ranges of heat, humidity, and temperature. Neither will it react with the fluid contents of the tank T to endanger life, limb and/or property due to adverse chemical reactions or fire within the tank T.

To illustrate the effectiveness of the audible alarm device 10, for example, if dry nitrogen under 40 pounds per square inch pressue is permitted to energize a conventional steam or air whistle 44, noise levels of at least 99 decibels or greater can be produced. This is sufficient for industrial applications or other high noise level environments.

In a preferred embodiment for the prevention of oil spills from storage and cargo tanks the spherical float 24 can be constructed from copper and dimensioned to be inches in diameter, thereby providing approximately pounds of lift in response to an overly high fluid level in the tank T. The mounting bracket 12, open frame 14 and the float cage 16 can be constructed of stainless steel and the air valve 26 can be a standard bronze air valve. The use of half-inch heavy duty galvaniz'ed pneumatic lines for themanifold 30 and the main supply header 40 is also contemplated.

In operation, referring to FIGS. 1, 2 and 3, the audible alarm device 10 is mounted in the tank T such that a liquid level Ll (indicated by the lowermost dotted line position in the tank T to FIG. 3) or less will have no effect on the audible alarm device 10. However, when the liquid level reaches the level L2 (indicated by the uppermost dotted line position in the tank T in FIG. 3) the spherical float 24 will be constrained to assume the dotted line position shown in FIG. 2. This causes the float 24 to direct an upward force against the foot 36B on the bell crank 36 forcing the said bell crank 36 to pivot about the point 38 and force the contact foot 36A down against the plunger 32 of the air valve 28. The resulting depression of the plunger 32 opens the normally closed air valve 28 and permits pressure from the supply header 40 and supply 42 to flow into the inlet portion 30A of the pressure manifold 30 and through the valve 28, out through the outlet 30B of the header 30 and into the gas whistle 44 to thereby sound an audible alarm indicating that the liquid level L2 has been achieved within the tank T.

Referring to FIGS. 4 and 5 there is shown a ship or barge generally designated 54 having four cargo tanks 56, 58, 60, and 62. An audible alram device 10 is disposed in a dome portion 46 of each of said tanks and similar alarm devices 10 are located in the rakes 54A and 54B of barge 54. Alarm devices 10 may either be the type disclosed in FIGS. 1 to 3 or the type shown in FIG. 7 to be described hereinafter. A common or central supply of nitrogen 42 is connected through supply header 40, which is connected to manifold 30 of each of the alarm devices 10. In the alternative a separate source of nitrogen may be provided for each of the alarm devices 10. The use of separate sources of nitrogen is particularly useful on ships or barges larger than 150,000 barrels. The use of separate sources eliminates the need for long lengths of pipe, thereby reducing the chance of leaks; increases the supply of dry nitrogen available for each alarm device; and localizes the supply of dry nitrogen in the immediate area of each tank or area being monitored.

Referring to the opeeration of the system disclosed in FIGS. 4 and 5 of the alarm devices 10 in tanks 56, 58, 60, and 62 will sound horns or whistles 44 upon the occurrence of an overflow and/or leakage condition in any of said tanks and alarm devices 10 in the rakes 54A and 54B of barge 54 will sound alarm horn or whistles 44 if the water in the rakes rises above a predetermined level commensuratefwith a sinking condition of the ship. Therefore, the system of FIGS. 4 and 5 comprises a fail safe alarm system which will warn the barge crew of any condition which might lead to an oil spill or dangerous condition on the ship.

Referring to FIG. 6 there is shown an embodiment of the present invention for automatically shutting down the pumping of oil or other fluid material from a loading dock to a barge 54. Barge 54 may be of the type illustrated in FIGS. 4 and 5 having at least four oil tanks, each of said tanks having an alarm device 10 disposed therein.

Each of the alarm devices 10 is connected to a common pressure switch 68 by suitable conduit means 64 connected to output manifold sections 30B of each of the respective alarm devices 10. Suitable check valves 66 may be provided in conduits 64' to restrict the flow of nitrogen to pressure switch 68 after the pressure builds up to a sufiicient level to trigger switch 68.

Pressure switch 68 may be any suitable commercially available type which generates an electrical output pulse or signal in response to a flueric or fluidic input signal. The output of pressure switch 68 is connected through electrical cable 70 to electrical connector 73 of the electrical system of the pumping means located on loading dock 53. An electrical cable 72 extends between electrical connector 73 and a power relay 75 which turns the power on and off to the pumping means. Said relay maybe located for example in the main pumping room of the loading dock. An electrical cable 71'is also provided which extends-from connector 73 to an electromagnetically actuated gate valve 74 located in the main supply line 78 of the oil pumping means. A manually operated gate valve 76 may also be provided in line 78.

In operation an overflow or leakage condition in any of the tanks on barge 54 will release nitrogen under pressure through outlet manifold sections 303 of alarm devices 10. This nitrogen will simultaneously be supplied to horns or whistles 44 through outlet sections 30B and to pressure switch 68 through conduits 64 by way of check valves 66. This will cause pressure switch 68 to generate an output control signal through electrical cables 70, 71, and 72 to the relay in the pump room and to electrically actuated gate valve 74. This output control signal causes the relay in the pump room to open shutting down the pumps and closes electrically actuated gate valve 74, which stops the flow of oil or fluid through conduit 78 from dock tanks 79 to the tanks on oil barge 54. Simultaneously with the shutting down of the pumping operation horns or whistles 44 are sounded warning the operator of the overflow or leakage conditions in the oil tanks being filled.

Referring to FIGS. 7 to 9 there is illustrated an alarm device for signaling either an overflow or leakage condition in a tank T having a dome portion 46 and a removable hatch 80. The alarmdevice of FIGS. 7 to 9 is substantially identical to the alarm device of FIGS. 1 to 3 in some respects in that the valve means 26, the manifold 30, and the bell crank 36 have substantially the same functions. However, float 24 is mounted for slidable movement on a vertically disposed rod 82 which also passed through a bore 84A in a slidable disc 84 mounted below float 24 and a bore 36C in bell crank 36. Float 24 rests on top of disc 84 and in the absence of the bouyant force of supporting fluid beneath disc 84, the weight of float 24 will force disc 84 downwardly along rod 82. The relative diameters of bore 36C and rod 82 must of course be such that the vertical arm of bell crank 36 may be moved laterally a sufficient distance with respect to rod 82 to permit bell crank 36 to pivot about point 38 a sufiicient amount to' depress valve actuator 32. Rod 82 may be attached to the walls of tank T by welding or any other suitable means.

The leakage condition-sensing means of the alarm device of FIGS. 7 to 9 includes disc 84, a pulley or reel 88, a cable 86 wound around reel 88, and a lever 90 supported about a pivot point 94. Pulley or reel 88 is pivotally mounted on lever 90 about pivot point 888 and may be adjusted through hatch 80 by rotating reel 88 to wind or unwind a selected amount of cable 86 and thereby adjust the height of disc 84. Reel 88 may be locked in any desired position by any suitable means. For example the periphery-of reel 88 may contain a series of apertures 88A which may be aligned with a locking pin 90A, which passes through a suitable aperture in lever 90. A second locking pin 92 may be provided for supporting lever 90, reel 88, and disc 84 just prior to a filling operation when tank T is empty. After the fluid in tank T reaches a predetermined minimum level which is sufficient to buoyantly support disc 84, locking pin 92 may be removed Locking pin 92 may be supported on a bracket 91 extending from support 12 or any suitable wall of tank dome 46. Locking pin 92 may be adjusted by reaching through the opening provided by hatch 80.

Referring to the operation of the alarm device of FIGS. 7 to 9 an overflow condition is sensed in substantially the same manner as described with respect to the alarm device of FIGS. 1 to 3. When the fluidlevel in tank T rises above a predetermined level L2, float 24 travels up rod 82 and presses against foot 36B of bell crank 36. This causes bell crank 36 to pivot about point 38 thereby depressing valve actuator 32, which opens valve 28 and releases nitrogen gas through manifold outlet section 30B to horn or whistle 44. If on the other hand a leak occurs in tank T the fluid level in tank T will fall to a predetermined minimum level L1, the weight of float 24 will cause disc 84 to slide down rod 82 pulling on cable 86, which will cause lever 90 to pivot about point 94 and depress valve actuator 32. In a like manner to the overflow sensor this will initiate the release of nitrogen to horn or whistle 44 to sound an alarm indicating that tank T is leaking.

From the foregoing, it can now be readily seen that the present invention satisfies a long-felt need in the art to aid in precluding environmental pollution due to oil spills and the like.

It should be understood that the present invention may be modified as would occur to one of ordinary skill in the art without departing from the spirit and scope of the invention.

What is claimed:

1. A system for monitoring and controlling the filled operation of a fluid storage tank comprising:

a source of dry nitrogen gas under pressure;

gas operated audible means external of said storage gas operated pressure switch means for generating an electrical output signal;

valve means mounted internally of said storage tank including pneumatic pressure lines interconnecting opposite sides of said valve means with said source and each of said audible means and said pressure switch means, respectively; and float means mounted internally of said storage tank, interconnected with said valve means, and responsive to at least one predetermined fluid level in said storage tank to actuate said valve means to transmit gas from said source through said pneumatic lines to said audible means and said pressure switch means simultaneously; pumping means for supplying fluid to said storage tank; and means responsive to said electrical output signal from said pressure switch means for shutting down said pumping means. 2. The invention of claim 1 wherein said pumping means comprises:

at least one pump; means for supplying electrical power to said pump;

and electrical switch means for turning off the supply of electrical power to said pump in response tov an electrical output signal from said pressure switch means. 3. The invention of claim 1 wherein said pumping means comprises:

at least one pump; 7 conduit means connected between said pump and said tank for supplying fluid to said tank; and electrically actuated gate valve means in said conduit means, said gate valve means being closed in response to an electrical output signal from said pressure switch means, thereby shutting down said pumping means. 4. The invention of claim 1 wherein said pumping means comprises:

at least one pump; means for supplying electrical power to said pump; electrical switch means for turning off the supply of electrical power to-said pump in response to an electrical output signal from said pressure switch means;

conduit means connected between said pump and said tank for supplying fluid to said tank;

electrically actuated gate valve means in said conduit means, said gate valve means being closed in response to an electrical output signal from said pressure switch means, thereby shutting down said pumping means.

5. The invention of claim 1 including check valve means in said pneumatic pressure lines between said valve means and said pressure switch means for restricting the flow of nitrogen gas to said pressure switch means after the pressure builds up to a sufficient level to trigger said pressure switch means.

6. The invention of claim 1 wherein one of said predetermined fluid levels in said tank corresponds to a leakage condition in said tank and said audible means is sounded and said pressure switch means is triggered in response to said leakage condition.

7. The invention of claim 1 wherein one of said predetermined fluid levels in said tank corresponds to an overflow condition in said tank and said audible means is sounded and said pressure switch means is triggered in response to said overflow condition.

8. The invention of claim 7, wherein said float means comprises:

a float in said tank;

a fluid pervious float cage containing said float and constraining same to a limited vertical displacement in response to varying fluid levels in said tank; and

sound said audible means in response to a second fluid level corresponding to a leakage condition in said tank. 12. The inventionof claim 11 wherein means are prolinkage means extending from said float cage to said vided for locking said lever means in a fixed position.

valve means for actuating said valve means; said float rising in said float cage and engaging said linkage means in response to said predetermined fluid level to constrain said linkage means to actuate said valve means and sound said audible means and trigger said pressure switch means.

9. The invention of claim 8, wherein said valve means is normally closed and said linkage means comprises:

pivot means on said valve means;

an operating plunger for said valve means; and

a bell crank lever pivoted intermediate the ends thereof on said pivot means;

said bell crank lever being rigidly affixed to said float on one end thereof and means engaging said operating plunger on the other end thereof.

10. The invention of claim 1 wherein a first predetermined fluid level in said tank corresponding to an overflow condition will sound said audible means'and trigger said pressure switch means and a second predetermined fluid level in said tank corresponding to a leakage condition will also sound said audible means and trigger said pressure switch means.

11. The invention of claim 10, wherein said float means comprises:

a float in said tank mounted for slidable movement on vertical rod means in response to varying fluid levels in said tank;

first and second linkage means extending from said rod means to said valve means for actuating said valve means, said float rising along said rod means and engaging said first linkage means to actuate said valve means and sound said audible means in response to a first fluid level corresponding to an overflow condition in said tank, said float moving down said rod means and engaging said second linkage means to actuate said valve means and 13. The invention of claim, 11 wherein said valve means is normally closed and said first linkage means comprises:

pivot means on said valve means;

an operating plunger for said valve means; and

a bell crank lever pivoted intermediate the ends thereof on said pivot means;

said bell crank lever having means for engaging said float on one end thereof and means engaging said operating plunger on the other end thereof.

14. The invention of claim 11, wherein said valve means is normally closed and said second linkage means comprises:

an operating plunger for said valve means;

lever means pivotally mounted at a first end thereof adjacent said valve means and having reel means mounted on a second end thereof, said lever means being constrained to engage and depress said plunger when pivoted downwardly about said first end;

disc means mounted for vertical movement on said rod below said float and being adapted to engage said float in response to said second fluid level corresponding to a leakage condition; and

cable means connecting said disc means to said reel means on said second end of said lever means.

15. The invention of claim 14, wherein one end of said cable means is wound about said reel means and said reel means is pivotally and adjustably mounted on said lever means, whereby said cable means may be selectively wound or unwound from said disc means to adjust the position thereof on said rod means.

16. The invention of claim 15 wherein means are provided for locking said reel means in selected positions. 

1. A system for monitoring and controlling the filled operation of a fluid storage tank comprising: a source of dry nitrogen gas under pressure; gas operated audible means external of said storage tank; gas operated pressure switch means for generating an electrical output signal; valve means mounted internally of said storage tank including pneumatic pressure lines interconnecting opposite sides of said valve means with said source and each of said audible means and said pressure switch means, respectively; and float means mounted internally of said storage tank, interconnected with said valve means, and responsive to at least one predetermined fluid level in said storage tank to actuate said valve means to transmit gas from said source through said pneumatic lines to said audible means and said pressure switch means simultaneously; pumping means for supplying fluid to said storage tank; and means responsive to said electrical output signal from said pressure switch means for shutting down said pumping means.
 2. The invention of claim 1 wherein said pumping means comprises: at least one pump; means for supplying electrical power to said pump; and electrical switch means for turning off the supply of electrical power to said pump in response to an electrical output signal from said pressure switch means.
 3. The invention of claim 1 wherein said pumping means comprises: at least one pump; conduit means connected between said pump and said tank for supplying fluid to said tank; and electrically actuated gate valve means in said conduit means, said gate valve means being closed in response to an electrical output signal from said pressure switch means, thereby shutting down said pumping means.
 4. The invention of claim 1 wherein said pumping means comprises: at least one pump; means for supplying electrical power to said pump; electrical switch means for turning off the supply of electrical power to said pump in response to an electrical output signal from said pressure switch means; conduit means connected between said pump and said tank for supplying fluid to said tank; electrically actuated gate valve means in said conduit means, said gate valve means being closed in response to an electrical output signal from said pressure switch means, thereby shutting down said pumping means.
 5. The invention of claim 1 including check valve means in said pneumatic pressure lines between said valve means and said pressure switch means for restricting the flow of nitrogen gas to said pressure switch means after the pressure builds up to a sufficient level to trigger said pressure switch means.
 6. The invention of claim 1 wherein one of said predetermined fluid levels in said tank corresponds to a leakage condition in said tank and said audible means is sounded aNd said pressure switch means is triggered in response to said leakage condition.
 7. The invention of claim 1 wherein one of said predetermined fluid levels in said tank corresponds to an overflow condition in said tank and said audible means is sounded and said pressure switch means is triggered in response to said overflow condition.
 8. The invention of claim 7, wherein said float means comprises: a float in said tank; a fluid pervious float cage containing said float and constraining same to a limited vertical displacement in response to varying fluid levels in said tank; and linkage means extending from said float cage to said valve means for actuating said valve means; said float rising in said float cage and engaging said linkage means in response to said predetermined fluid level to constrain said linkage means to actuate said valve means and sound said audible means and trigger said pressure switch means.
 9. The invention of claim 8, wherein said valve means is normally closed and said linkage means comprises: pivot means on said valve means; an operating plunger for said valve means; and a bell crank lever pivoted intermediate the ends thereof on said pivot means; said bell crank lever being rigidly affixed to said float on one end thereof and means engaging said operating plunger on the other end thereof.
 10. The invention of claim 1 wherein a first predetermined fluid level in said tank corresponding to an overflow condition will sound said audible means and trigger said pressure switch means and a second predetermined fluid level in said tank corresponding to a leakage condition will also sound said audible means and trigger said pressure switch means.
 11. The invention of claim 10, wherein said float means comprises: a float in said tank mounted for slidable movement on vertical rod means in response to varying fluid levels in said tank; first and second linkage means extending from said rod means to said valve means for actuating said valve means, said float rising along said rod means and engaging said first linkage means to actuate said valve means and sound said audible means in response to a first fluid level corresponding to an overflow condition in said tank, said float moving down said rod means and engaging said second linkage means to actuate said valve means and sound said audible means in response to a second fluid level corresponding to a leakage condition in said tank.
 12. The invention of claim 11 wherein means are provided for locking said lever means in a fixed position.
 13. The invention of claim 11 wherein said valve means is normally closed and said first linkage means comprises: pivot means on said valve means; an operating plunger for said valve means; and a bell crank lever pivoted intermediate the ends thereof on said pivot means; said bell crank lever having means for engaging said float on one end thereof and means engaging said operating plunger on the other end thereof.
 14. The invention of claim 11, wherein said valve means is normally closed and said second linkage means comprises: an operating plunger for said valve means; lever means pivotally mounted at a first end thereof adjacent said valve means and having reel means mounted on a second end thereof, said lever means being constrained to engage and depress said plunger when pivoted downwardly about said first end; disc means mounted for vertical movement on said rod below said float and being adapted to engage said float in response to said second fluid level corresponding to a leakage condition; and cable means connecting said disc means to said reel means on said second end of said lever means.
 15. The invention of claim 14, wherein one end of said cable means is wound about said reel means and said reel means is pivotally and adjustably mounted on said lever means, whereby said cable means may be selectively wound or unwound from said disc means to adjust the positIon thereof on said rod means.
 16. The invention of claim 15 wherein means are provided for locking said reel means in selected positions. 